explanation on light setup:
I used a hdri-image to light the scene but disabled primary visibility cause I need a dynamic background. therefor I mapped a procedural shader to the camera´s environment tab - used an envSky_node. under it´s Cloud Attributes tab I mapped a 3dcloudTexture. it´s placement_node´s Translate attribute is keyframed from 0 - 1 on x-axis over the whole scene - so the clouds are moving slightly. in the envSky_node the elevationAttr is animated as well from -20 to bout 70, so I get a anim from dawn till dusk. this is my background image for the scene. reflections tho come from the HDRI cause the envSky is just a imageplane and doesn´t enlight the scene. It could when pluging the output color to the cameras backgroundColorAttr, but that doesn´t give a good lighting.
in addition I placed a directional light with the same angle as the inital elevation direction, grouped the light to itself and connected the elevationAttr into the lightGroup´s X-rotation. so the directLight moves with the sun from the envSky shader and I get an additional light casting raytraced shadows which seem to come directly from the procedural background image.
well, so much for initial light setup. next big thing will be the shaders which give me the creeps allready.
everything starts and ends in the right place at the right time.